In the case of receiving a broadcasting signal transmitted from a stationary satellite above the equator, it is a general practice to use an antenna for exclusive use in reception of electric waves from satellites, such as a parabolic or plane antenna. In the case of receiving broadcasting signals from a plurality of stationary satellites by a single antenna, it is necessary to have the single antenna track the respective stationary satellites.
For example, Japanese patent opening gasette No. H4-207206 discloses a device for this purpose. This device is provided for receiving electric waves from two satellites launched up above the equator and arranged to adjust the elevation of a parabolic antenna by hand and the azimuth thereof by an actuator so that, at the time of factory shipment, the elevation is adjusted to a value needed for receiving the signals from the respective satellites at a previously known set-up position of the parabolic antenna and, after it is really set up at the set-up position, the azimuth of the parabolic antenna is adjusted by driving the actuator so as to enable reception of the signals from the respective satellites. Adjustment of the azimuth is effected on the basis of data previously set in a control section of the actuator respectively in accordance with an azimuth needed for receiving the electric waves from both satellites at the set-up position.
In the case of using such a device at a position other than the predetermined set-up position, in addition to readjustment of the elevation, it is necessary to newly set in the control section of the actuator such data for adjusting the azimuth as obtained by actually changing the azimuth of the parabolic antenna to seek an azimuth which enables preferable reception of the electric waves from the respective satellites.
The receiving devices of this kind for receiving electric waves from a plurality of satellites include a device which indicates what channel is received from which satellite, as shown especially in Photo. 4 in page 18 of an article entitled "Satellite PCM World" (made by Mitsuru Hamano) inserted in pages 16 to 24 of "DENPA GIJUTSU KYOKAIHO (Radio Engineering & Electronics Association)" Vol. 165 published Mar. 1, 1992 by Japanese foundation of Radio Engineering and Electronics Association, for example. The indication includes the name of each satellite and the name of a specific channel, which is now received, of a plurality of channels transmitted from each satellite.
For example, a number of satellites have been launched above the equator between 69 and 143 degrees of west longitude for U.S. domestic use. Since the U.S. territory is extensive, it is not always possible to receive the signals from all satellites for U.S. domestic use at any receiving position within the United States. The satellites whose signals can be received at a specific receiving position are, limited to a few satellites situated adjacent to each other from east to west in geosynchronous orbit. However, the user of a satellite signal receiving device does not always know the names of both satellites respectively positioned at the eastmost end and westmost end of the receivable range for the position of use of the receiving device and he may intend to receive an electric wave from a particular satellite which is further west than the westmost satellite on the receiving threshold, for example. Accordingly, if the receiving device is provided with a display device for displaying a map including the receiving position and the satellite whose signal is to be received in connection with the map, it is possible to judge whether the particular satellite is a satellite whose signal can be received at the receiving position or not.
An object of this invention is to satisfy setting for receiving electric waves from a plurality of satellites when a receiving device is set up.
Another object of this invention is to enable indication of the position of a satellite whose signal is now received.